In the past, 3-acryloyloxypropyl trimethoxysilane, 3-acryloyloxypropylmethyl dimethoxysilane, 3-methacryloyloxypropyl trimethoxysilane, 3-metacryloyloxypropylmethyl dimethoxysilane, and other organosilicon compounds with monovalent organic groups containing acryloyloxy groups or monovalent organic groups containing methacryloyloxy groups and hydrolytic groups bonded to silicon atoms have been used as silane coupling agents and raw materials for the production of crosslinkable polyolefinic resins.
However, due to the fact that the monovalent organic groups containing acryloyloxy groups or monovalent organic groups containing methacryloyloxy groups and hydrolytic groups were bonded to the same silicon atoms, the problem with these organosilicon compounds was that when they were used as silane coupling agents for the surface treatment of inorganic fillers, these functional groups ended up concealed in the crosslinked coating formed via the condensation reaction and hydrolysis, so that the effectiveness of the surface treatment was lower than expected. For this reason, when inorganic fillers obtained by surface treatment using these organosilicon compounds were compounded with silicone rubber compositions, sufficient fatigue durability could not be imparted to the silicone rubbers obtained by curing them. Also, when these organosilicon compounds were copolymerized with various olefins as raw materials for the production of crosslinked polyolefinic resins, these functional groups ended up concealed in the polyolefinic resin, and, as a result, the crosslinkability of the polyolefinic resin was lower than expected.
In the past, the authors of the present invention offered organopentasiloxanes with acryloyloxy-containing monovalent organic groups or methacryloyloxy-containing monovalent organic groups and hydrolytic groups bonded to silicon atoms and a process for their production (see Japanese Unexamined (Kokai) Patent Publication No. Hei 05(1993)-86075). The process for the production of the organopentasiloxane offered in Japanese Unexamined (Kokai) Patent Publication No. Hei 05(1993)-86075 was characterized by subjecting organopentasiloxane having a hydrogen atom bonded to a silicon atom at one end of the molecular chain and a hydrolytic group bonded to a silicon atom at the other end of the molecular chain and an alkene or alkylenoxyalkene containing methacryloyloxy groups to a hydrosilylation reaction.
However, the problem with the process for the production of the organopentasiloxane offered in Japanese Unexamined (Kokai) Patent Publication No. Hei 05(1993)-86075 was that when it was used to produce organopentasiloxanes, various side reactions were generated. When, for example, 1,1,1 -trimethoxy-3,3,5,5,7,7,9,9-octamethylpentasiloxane and allyl methacrylate were subjected to a hydrosilylation reaction, a propene-releasing b-elimination reaction described below would take place, producing the target organopentasiloxane with a 3-methacryloyloxypropyl group bonded to a silicon atom at the end of the molecular chain along with organopentasiloxane with a methacryloyloxy group bonded to a silicon atom at the end of the molecular chain and organopentasiloxane with a propyl group bonded to a silicon atom at the end of the molecular chain as by-products, which decreased the yield and purity of the target product. ##STR2##